1. Field of the Invention
This invention generally relates to character recognition technology, and, in particular, to a method for recognizing a character by variably subdividing a character region in which a character to be recognized is located. The present invention also relates to a method of subdividing a character region for use in character recognition.
2. Description of the Prior Art
In character recognition of a written, typed or printed character by device, a character to be recognized is first optically read by a scanner to define a binary image of the character, and, then, a character region containing therein the thus defined binary image is divided into a plurality of sub-regions, which is followed by the step of extracting features for each of the sub-regions. In the prior art character recognition technology, the division of region was carried out using fixed subdividing points, as described in the Japanese Patent Laid-Open Pub. No. 56-110191, or by variably determining subdividing points utilizing a center of gravity of the contour distribution of a character to be recognized, as described in "OKI ELECTRIC RESEARCH AND DEVELOPMENT", Dec. 1983, 121, Vol. 50, No. 3, pp. 77-82. However, in the former method, the fixed subdividing points were often found to be inappropriate due to deformations present in a character to be recognized, so that features of the character could not be extracted properly, thereby degrading the character recognition capability. Thus, the fixed subdividing point method has a problem of incapability to cope with character deformations. On the other hand, the latter method using a center of gravity is less susceptible to character deformations; however, the amount of calculations required for subdivisions of a character region is enormous since it utilizes a center of gravity of the contour distribution, so that this method tends to be slow.
In order to cope with the above-mentioned problems, there has been proposed an improved character recognition method as disclosed in the Japanese Patent Application No. 59-217760, which was assigned to the assignee of the present assignee and which was described in U.S.S.N. 915,285, filed Oct. 3, 1986, which, in turn, was also assigned to the assignee of this application and is incorporated herein by reference. The improved character recognition method described in the above-identified U.S.S.N. 915,285 has obviated most of the above-described disadvantages of the prior art. However, there still remains area of further improvements particularly for discrimination between similar characters and for recognition of deformed or low quality characters, printed or handwritten.